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Posts Tagged ‘constraints’

The title of last week’s post was a play on a Mark Twain quote. This week I draw from a more contemporary source: The Muppets. Some episodes of the legendary family TV show featured a skit called “Pigs in Space.” In my head I’m reading “SoCs in Space!” with the same booming intonation used on the show for “Pigs in Space” to lead into a somewhat more serious discussion about the use of advanced chips in extreme conditions.

My prompt for this particular post came not from TV, but from an announcement yesterday that VORAGO Technologies is offering an ARM-based microcontroller (MCU) “designed specifically for radiation and extreme temperature operation without up-screening.” In other words, they ship an MCU that’s ready to use in such traditionally challenging environments as automobiles and industrial controllers as well as, yes, space. That got me thinking about even more complex chips such as SoCs and the extreme conditions they might have to face.

With a nod to Mark Twain, this week I’d like to comment on a recent three–partseries with the provocative title “Are Simulation’s Days Numbered?” The articles were transcribed from one of the “experts at the table” events that SemiconductorEngineering does so well. Breker wasn’t involved in this particular roundtable, but I enjoyed reading the series and found that it stirred up some thoughts. As a blogger, of course I’m going to share them with you and I hope you enjoy them in turn.

Let’s get this out of the way immediately: in three parts and more than 5,000 words, there was no mention of portable stimulus. That might not seem too surprising given the title, but in fact verification portability both from IP to system and from simulation to hardware arose during the discussion. So I’ll comment on that but, given my background as a vendor of formal EDA tools and reusable IP blocks, there are a few other topics that also piqued my interest.

Ever since Accellera started the Portable Stimulus Working Group (PSWG), this emerging technology has generated a lot of buzz both within the EDA industry and among our semiconductor and systems customers. As the pioneer in this technology we get a lot of questions about what portable stimulus is, why it is different from the Universal Verification Methodology (UVM) and other established approaches, and why anyone would need it.

We’ve devoted quite a few posts to this topic in The Brekker Treker blog, stretching back two years to when Accellera first set up a proposed working group (PWG) to survey the industry and decided whether standardization of portable stimulus was feasible and desirable. Given the many posts scattered throughout the past two years, we thought that we would take this opportunity to give readers new to this topic a guided tour of the information that we have available.

Last week, we used an update on the Accellera Portable Stimulus Working Group (PSWG) presented at the Design and Verification Conference and Exhibition (DVCon) as a jumping-off point to discuss the status of this standardization effort and some key aspects of the three proposals currently under consideration. We were not the only blog to cover portable stimulus topics from DVCon; Brian Bailey of SemiconductorEngineering and Bernard Murphy from SemiWiki also posted their observations.

Earlier this week, EDACafe blogger colleague Peggy Aycinena posted a thought-provoking look at PSWG and the portable stimulus challenge. In regards to the scope of the proposed standard, she noted “a distinct wow factor in all of this, it’s so comprehensive” and said “this whole effort seems massive to me.” Today we’d like to respond to Peggy’s comments and questions, noting both the challenges of a portable stimulus standard and the availability of a working solution today.

As all of our regular readers are aware, the software-driven SoC verification space pioneered by Breker is becoming more of a mainstream approach every day. One good barometer for the industry shift now underway is the standardization effort in progress within the Accellera Portable Stimulus Working Group (PSWG). The amount of interest in this standard has skyrocketed recently, and portable stimulus was a hot topic at the Design and Verification Conference and Exhibition (DVCon) two weeks ago.

As we promised when we first began discussing the PSWG, we don’t believe in sharing internal details of standardization work in a public blog. However, the group was offered a slot to present an update at an Accellera-sponsored lunch during DVCon. So the PSWG put together a set of slides with information to share publicly and Vice-Chair Tom Fitzpatrick of Mentor did a nice job of presenting them. For those of you who could not attend, we’ll summarize the current status in today’s blog post.

The past twoweeks, we’ve been having a bit of fun playing alchemist and letting readers in on some of the deep, dark secrets of graph-based verification technology. This week, we conclude the series by showing some additional capabilities for our scenario models that are easy to control and view in a graph visualization. Our point is, of course, that graphs are a natural way to represent data flow and verification intent with no advanced degrees from MIT, IIT, or Hogwarts required.

As a quick reminder, graph-based scenario models begin with the end in mind and show all possible paths to create each possible outcome for the design. They look much like a reversed data-flow diagram, with outcomes on the left and inputs on the right. Breker’s Trek family can traverse the graph from left to right, randomizing selections to automatically generate test cases tailored to run in any target platform. Today, we continue using our example of a scenario model to verify that an automobile can move forward or stop.

Last week, we began exploring some of the ancient, mysterious powers of graph-based scenario models to show their power for verification and ability to capture the verification space, many aspects of the verification plan, and critical coverage metrics. We’re just kidding about the first part; there’s nothing at all mystical or magical about graphs. In fact, this series of posts is intended to show the opposite and demonstrate with a easy-to-follow example the value of graphs.

As we noted in our last post, graph-based scenario models are simple in concept: they begin with the end in mind and show all possible paths to create each possible outcome for the design. They look much like a reversed data-flow diagram, with outcomes on the left and inputs on the right. An automated tool such as Breker’s Trek family can traverse the graph from left to right, randomizing selections to generate test cases that can run in any target platform.

Those of us of a certain age will remember the secret decoder rings promoted by various products and TV shows. They generally used a simple substitution code to map letters to numbers. According to Wikipedia these have been offered as recently as 2000, so perhaps they are known to younger readers as well. What’s germane to today’s blog post is that formal services company Oski Technology has cleverly used this device as a graphical element in promoting its “Decoding Formal” Club series.

I’ve reported before fromtheseevents, which I believe have been very effective at advocating for formal analysis, sharing tricks and techniques, and demystifying what was once regarded as an arcane academic approach to verification. Last week I attended another Decoding Formal Club forum and, as usual, was impressed by the depth of the presentations. Since formal is always a popular topic among readers of The Breker Trekker, I’m going to share a few highlights from that afternoon.

Last May, I published two blogposts on the presentations made at a “Decoding Formal Club” event hosted by the smart folks from Oski Technology at the Computer History Museum in Mountain View. With everything else going on, I didn’t manage to make it to another of their regular meetings until last week. The first event of 2015 was very interesting, so again I’m returning to the popular topic of formal analysis and playing reporter. The line between media and blogging is rather thin these days anyway.

This edition of Decoding Formal featured three talks, one an end-user case study and the other two instructional in nature from well-known formal experts. I found all three worthwhile and will do my best to communicate some of the main points made. I also have to mention the final presentation, more a performance than a talk, by the inimitable and irrepressible Clifford Stoll. Lately he’s been manufacturing and sellingKlein bottles, which you may remember from a geometry teacher trying to mess with your mind.

Last week I used a talk by Vigyan Singhal, CEO of formal consulting experts Oski Technology, as the springboard for a blog post on how to extend verification planning for formal analysis and graph-based SoC verification. This week, I’m using a panel held at that same “Decoding Formal Club” meeting as the starting point for my thoughts on how to establish an effective team to use relatively new verification technologies such as formal and graphs.

The second half of the meeting was a panel on “How to Build a Productive Formal Team” moderated by Harry Foster from Mentor. The participants included a nice mix of users, while Vigyan rounded out the panel with his unique blend of formal tool development and hands-on usage with many customers. Although there wasn’t much controversy per se, it was clear that everyone had different experiences leading to different opinions on how to build a strong formal team.